Internal combustion engines generate various combustion by-products in the exhaust gas during the course of engine operation. Under some conditions, it may be desirable to control the production (amount, rate, etc.) of one or more selected exhaust components. For example, under some conditions, to meet stringent emissions criteria, it may be desirable to control the production of NOx species and/or particulate matter (PM) in the exhaust gas.
Various engine configurations, fuel types, additives, and exhaust after-treatment systems have been developed. As such, it may be desirable to provide additional improvements in controlling the emission of exhaust components. Furthermore, it may be desirable to design an emissions control system so that it can be installed in various vehicle systems without losing emissions performance.